Belt feed mechanisms for automatic firearms



Jan. 25, 1966 B. MAILLARD BELT FEED MEGHANISMS FOR AUTOMATIC FIREARMS 4 Sheets-Sheet 1 Filed Dec. 23 1963 Jan. 25, 1966 B- MAILLARD BELT FEED MEGHANISMS FOR AUTOMATIC FIREARMS Filed Dec. 23 1963 4 Sheets-Sheet l fly?.

Jan. 25, 1966 B. MAILLARD 3,230,828

BELT FEED MEcHANIsMs Foa AUTOMATIC FIREARMS Filed Dec. 25 1963 4 Sheets-Sheet 5 Jan. 25, 1966 B. MAILLARD BELT FEED MECHANISMS FOR AUTOMATIC FIREARMS 4 Sheets-Sheet 4 Filed Dec. 23 1963 United States Patent O 3,230,828 BELT FEED MECHANISMS FUR AUTOMATIC FIREARMS Bernard Maillard, Geneva, Switzerland, assigner to Brevets Aero-Mecaniques SA., Confederation of Switzerland, lGeneva, Switzerland Filed Dec. 23, 1963, Ser. No. 332,827 Claims priority, application Luxembourg, Dec. 21, 1962, 42,912 1 Claim. (Cl. 89-33) The present invention relates to belt feed mechanisms for automatic firearms of the type including a toothed rotor, the term belt feed mechanism being meant to include any mechanism capable of conveying the cartridges toward the firearm and of feeding them successively thereto during firing. 'Ihe invention is more especially but not exclusively concerned with firearms the breechblock of which is released through means responsive to an effect other than the recoil of the firearm .for instance through a gas tap.

The chief object of the present invention is to provide a mechanism of this type which is better adapted to meet the requirements of practice than those known up to now.

The invention relates, in a general manner, to a mech anism of the kind in question actuated by a power device supplying a power impulse every time a shot is fired, for instance actuated by the firearm itself during at least a portion (hereinafter called active portion) of every recoil thereof with respect to its support and to the feed belt guiding device rigid with said support, the belt being, of course, moved by the rotor a distance equal to a complete pitch every time a shot is fired, such a mechanism including, between said power device and said rotor, a transmission system including a first rotary element rotated by every recoil of the firearm through an angle equal to, or just a little greater than, 21r/n and a second rotary element consisting of a toothed rotor having n teeth and coaxial with the first rotary element, between which elements there is provided an angular play corresponding to a portion of a complete pitch of the second element, this play tending to be maintained by a prestressed torsional resilient system such that, if, during a given power impulse, the second element does not turn through a sufiicient angle under the effect of the thrust transmitted by said resilient system, the latter is torsionally urged until, the play being eliminated, the first element imperatively drives the second one in rotation by abutment against it.

According to the present invention, said resilient system is constituted by two torsion bars housed coaxially one inside the other the whole of these two bars being itself housed coaxially in the rotor shaft, these two bars being rigidly connected together at one end, where they are freely journalled in the corresponding end of the rotor shaft, said bars being secured, at the other end, respectively to said first and second elements.

Other features of the present invention will result from the following detailed description of an embodiment thereof in which:

FIG. l is a general elevational view of a firearm provided with a belt feed mechanism according to the invention;

FIG. 2 shows, on an enlarged scale, said belt feed mechanism, in longitudinal section along parallel hori zontal planes and in particular along IIa-Ila and IIb- IIb of FIG. 4;

FIG. 3 is a sectional View on the line III-III of FIG. 2;

FIGS. 4, 5 and 6 show this belt feed mechanism in section on the line IV-IV of FIG. 2, but at three different times of its operation, respectively;

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FIG. 7 is an elevational view in the direction of the arrows VII- VII of FIG. 2 with portions in section;

FIG. 8 is a section on the line VIII-VIII of FIG. 2, this section being shown rotated through 9i);

FIG. 9 is a partial sectional view on the line IX-IX of FIG. 8;

FIG. 10 is a sectional view on the line X--X of FIG. 2;

FIG. 11 is a sectional view on the line XI-XI of FIG. 10;

FIG. l2 is an explanatory diagram relative to the device for stopping firing at the end of a belt.

It will be supposed in what follows that the belt feed mechanism that is described is to be used in connection with an automatic firearm fed with ammunition by means of a cartridge belt with open links, this firearm being controlled, for the release of its breechblock, by a gas tap system.

It will also be supposed:

That the automatic firearm essentially comprises a barrel 1 rigid, at the rear thereof, with a breech case 2 in which reciprocates a breechblock 3 urged forwardly by a recuperator spring 4 and controlled, concerning its release, by a gas tap system 5;

That the whole is mounted slidable in a fixed support or cradle 6, a resilient system 7 being interposed to absorb the recoil of the firearm with respect to its support and to return it forwardly;

That a plate 8 rigid with support 6 is provided to receive the belt feed mechanism 9 which will be hereinafter described, said plate 8 being for instance linked to support 6 through an arm 10 and sliding relatively to the upper edge of the breech case during the reciprocating movements of the firearm; and

That plate 8 is provided with means for securing the belt feed mechanism thereto in a detachable fashion, such means being for instance constituted, at the front, by a tenon-and-mortise connection 11 and, at the rear, by a retractable locking finger 12.

According to a conventional arrangement, shown by way of example, the belt feed mechanism is operated by the displacement of the firearm proper during at least a portion of its recoil with respect to support 6i, this displacement being imparted to the belt through a transmission system which will now be described.

This transmission system includes a -first rotary element 13 rotated, every time a shot is fired, under the effect of recoil of the firearm, through an angle equal to or higher than Zar/n, and a second rotary element consisting of a toothed rotor 14 having n teeth and coaxial with said first rotary element, this rotor being intended to drive the cartridge belt with a step by step i motion to feed the firearm, every angular displacement of the rotor being equal to 21r/n, i.e. the pitch An angular play X corresponding to a portion of a complete pitch of the rotor is provided between elements 13 and 14. This play tends to be maintained by a prestressed resilient system working torsionally and such that if, during a given driving impulse, rotor 14 does not rotate sufficiently under the effect of the stresses transmitted by said resilient system, the latter is urged torsionally until, play X being absorbed, rotary element 13 comes to drive the rotor imperatively, by abutment.

Now, according to the invention, said resilient system consists of two torsion bars, one of which (inner bar 15) is housed coaxially inside the other (outer tubular bar 16), these bars being rigidly connected together on one side, through their respective ends located on this side, the whole being disposed coaxially inside the rotor shaft.

The active end of one of the torsion bars, 15 inthe embodiment shown, is angularly fixed, through splines,

r`3 to an intermediate elementy consisting of a rotary driving piece 17 coaxial with rotor 14 the above mentioned play X being provided between this driving piece 17 and rotor 14.v The ractive'endl of the other bar is angularly fixed,

for instance ,through splines, to rotor 14.

he, otherend 18 of the whole is `freely journalled in the corresponding end of the rotor shaft.

...Between `driving vpiece 17 and the casing of the feed mechanism there is provided a pawl and ratchet device fv 1,9,.such that piece 17 cannot rotate in a direction opposed to the normal direction of rotation of the rotor (direction ,1,- inawhich said rotonmustrotate to convey the cartridges to the firearm).

:Finally-,there is ,also interposed, betweenrotary element 13 anddrivingpiece117, a unidirectional'clutch de- ...viCe;20f suc hthat element13is preventedvfrom rotating with respect todriving piece 17 inthe direction corre- 4Vsponding to that of the normal rotation of rotor 14.

It,willy berunderstood that, with ,suchan arrangement, ont every rotationL of rotaryelement 13, a little greater than one pitch rotor 14 will be rotated through an angle equal to one pitch but thatif after the end of the active portion of the recoil of the firearm, rotor 14 has not yet completeditsirotation through one pitch, lthe resilient -4 system willcontinue to act upon said rotor 14 andthe re- .Y eoihenergy collected by element 13.will still be transmitted to the rotor. l StilLaccording tothe invention, :the tubular wall of torsion bar 1 6 is advantageously provided with a plurality of ,holes 21 which,.in the casefof a bar having an internal diameter averaging 8 mm., an external diameter averaging12 .mnLfand a usefullength averaging 200 mrn., may ,Lbeeither circular, with av diameterl averaging 4 mm., or feofnelongated shape having forinstance a width of 3 mm. Y.and a.length ofl l mm.,.said holes being disposed in rows lofafoursee FlG; 3) .thefdistance between two consecutive rods, in the direction of the. bar, being of the order lof 8mm.

fSuchanfouterfbar' .16 will be advantageously combined Awithaninner bar 15 having a diameter of the order of 6mm.

Some other characteristics of the feed mechanism will be hereinafter described but mostofthe elements of said mechanism, concerning thegeneral arrangement and the means for guiding the cartridges toward .the feed passage V22, of vthe .rearrnand also for tearing off the links and -evacuating them through a passage Z3 are fully described in the U.S.Patent` No. 2,821,888 .to Bernard Maillard v ofFebruary 4, 1958 for. Belt Feed yMechanisms for Automatic Firearms.

l--Inftbis prior patent the two torsionbars,instead of being 'coaxial to each other. and directly assembled together were parallel to, and at a distance from, each other, which constituted a complication Aand increased friction.

The firearm barrel 1 carries,-pivotally mounted there- Von (FIG. 9) aiinger-the rear end 24 of which acts as a cam extending between a roller journalledfabout an axis xed'with'respect to-thefeed mechanism casing and a movable roller- 26 slidablevertically with respect to e said casing.

i 32 xed with respect to the above mentioned breech mechanism casing, said push-piece being pivotally connected, about axis 27a, to the arm 27 of a lever pivoted at 30 to the casing, the other arm 28 of this lever meshing through a toothed sector 29 integral therewith, with teeth integral with the first rotary element 13. A spring 33 urges push-piece 31 toward movavble roller 26.

According to the embodiment illustrated by the drawings, the whole of movable roller 26, push-piece 31, lever 27, 28 and toothed sector 29 which meshes with pinion 13 is disposed in a separate casing 34 located at the front of the feed mechanism frame.

Driving piece 17, of tubular shape, is joui-nailed in the front and rear walls, respectively 35 and 36, of this casiV ing. It includes an extension, located on the inside of the feed mechanism casing and forming a sleeve Which surrounds the hollow shaft 38 of the rotor, with the iriterposition of dogs .39 constituting the front and rear abutments which determineth'e above mentioned play X.

Said sleeve 37 also carries the teeth 40 of pawl and ratchet device 19, the pawl 41 of which is pivoted about an axis fixed to the frame.

As for pinion 13, it is freely rotatable about driving piece 17. It carries ratchet teeth 42 cooperating with corresponding teeth 43 carried by aiiange 44 rigid with driving piece 17 andtherefore with sleeve 37. Said pinion 13 is slidableaxially on driving piece `17 .and it ispushed l back by a springl 45 whichtends to apply against each other the two sets of teeth 42 and 43 which cooperate to sgether to constitute theunidirectional clutch devicef.

. Itwillbe readily junderstood that the device above `described is much simpler `andtherefore stronger and Imechanism, is arranged in such manner that, as long a'S automatic iiring takes place, the cartridges engaged inthe rotor 4 keep, aga-inst the action of a spring46 and by acting upon the convex active portion 47 of an oscillating arm 48, said armf48appliedyagainst the shaft38 of rotor 14, thisarm 48 being allowed to pivot, and thus tostop ring, afterthe passage, opposite said active portion 47,

. of Athe last cartridge a (FIG. l0) ofthe belt, the relative position of theactive portion 47 of said arm with respect tothe Vxed frame of the mechanism (therefore with re- `spect to rotor 14) being such that, when arm 48 is allowed to pivot, firing is stopped while there remains in the Said arm 48 isdisposed at. therear of the mechanism frame and is pivotable about an axis 49 (FIG. 10). During automatic firing, this arm is retracted between .the parallel wallsr 50 of an annular groove 51 provided in apiece coaxial with the hollow shaft38 of the rotor. The active portion 47 of said arm has the `shape of a circular `arc concentric with rotor 14, which arc, when seen according to FIG. 10, wherearrn 48 is shown in solid lines as engagedin groove 51, coincides substantially with the corresponding portion of the surface 59 enveloping the rear portion of the cartridges driven by rotor 14.

It will be understood that, with such an arrangement,

if active portion 47 is giventhe proper position and shape, the last cartridge a of the belt is capableof keeping arm 48 in groove 51 until said last cartridge has come into the position corresponding to the time when tiring should be stopped. Spring46 then causes arm 48 to move out from groove 51, as shown in dot-and-dash lines in FIG.10, which, through suitable transmission means, retracts, with respect to a movable abutment 53, a stop 54 which, when retracted, enables movable abutment 53 to shift (under the action of a spring not shown by the drawings) from the position it occupied up to-then (in solid lines in FIG. 12) and which corresponded to automatic tiring, to another position (in dot-and-dash lines in FIG. 12) for which tiring is stopped. Y

Concerning the transmission means to be interposed between, on the one hand, movable abutment 54, on the other hand, the sear mechanism A of the firearm and, still on the other hand, the trigger mechanism B of said arm7 it is possible to make use of any suitable construction, known in itself, for instance that diagrammatically illustrated by FIG. 12 and which needs not be described here.

Such a feed mechanism requires for its operation only sixty percent of the energy collected from the recoil of the rearm: which was to be used for actuating the feed mechanism described in the above mentioned prior patent.

The feed mechanism according to the present invention is simpler, cheaper, lighter and more resistant than that of the prior feed mechanism described in the prior patent.

In a general manner, while the above description discloses what is deemed to be a practical and eliic-ient embodiment of the present invention, said invention is not limited thereto as there might be changes made in the arrangement, disposition and form of the parts without departing from the principle of the invention as comprehended within the scope of the appended claim.

What I claim is:

In combination with an automatic firearm system including a fixed support and a firearm proper movable longitudinally with respect to said support under the effect of recoil, with elastic means for returning said Afirearm proper in the frontward direction after every recoil thereof, said firearm including a breech case, a 'breechblock slidable longitudinally in said breech case between a front position and a rear position, and releasable means for holding said breechblock in said rear position thereof, a belt feed mechanism for said firearm which comprises, in combination, la cartridge belt constituted by a plurality of cartridges and links for interconnecting them, means for guiding said cartridge belt with respect to said support, a frame rigid with said guiding means, a rotary element and a rotary piece both journalled with respect to said frame about an axis parallel to the line of tiring of said firearm, unidirectional clutch means between said support and said rotary piece adapted to permit rotation of said rotary piece in only one direction of rotation, means operative by the longitudinal recoil and counter-recoil displacements of said firearm with respect to its support for imparting rotary movements to said rot-ary element in response to said firearm longitudinal displacements, unidirectional clutch means between said rotary element and said rotary piece for imparting to said rotary piece step by step rotations in said direction in response to said rotary movements respectively, with a given angular amplitude for every step, a toothed rotor journalled with respect to said frame about said axis, said rotor including a tubular shaft and teeth carried by said rotor shaft, the teeth of said rotor `being adapted to engage between the cartridges of said belt, cooperating means angnlarly fixed with respect to said rotary piece and to said rotor, respectively, for positively limiting the angular displacement of said rotary piece and said rotor with respect to each other to a given angular play smaller than said angular amplitude, .a torsion bar housed in said rotor shaft coaxially therewith, a tubular torsion bar coaxially surrounding said rst mentioned torsion bar and housed in said rotor shaft, said two torsion bars being rigidly connected together at one end and being freely journalled at said end in said rotor shaft, the other end of one of said torsion bars being fixed angularly to :said rotary piece and the other end of the other of said torsion bars being fixed angularly to said rotor, and an larm operatively connected with said releasable means adapted to be applied. As long as automatic firing is to go on, by the cartridges engaged in said rotor in retracted position toward the shaft of the rotor, this arm being adapted to pivot, after the 4passage opposite it, of the last cartridge of the belt that is being fired, into the position where it causes said releasable means to stop said breechblock in the rear position thereof, the relative position of said arm with respect to said fixed support being such that, when said arm is left free to leave said retracted position thereof, firing is stopped while there is still in the feed mechanism a number of cartridges at least equal to two.

References Cited by the Examiner UNITED STATES PATENTS 2,481,726 9/1949 Assis-Fonseca 89-33 2,644,365 7/ 1953 Maillard 89-33 2,756,537 7 195 6 Maillard 89--33 2,821,888 2/1958 Maillard 89-33 2,924,150 2/1960 Maillard 89-33 BENJAMIN A. BORCHELT, Primary Examiner.

FRED C. MATTERN, IR., Examiner. 

